Polyfluorophenyl phosphate esters



United States Patent 3,341,631 POLYFLUDROPHENYL PHOSPHATE ESTERS (Ihristian A. Seil, Santa Monica, Robert H. Boschan, Los

Angeles, and James P. Holder, Woodland Hills, Caliil, assignors to McDonnell Douglas Corporation, Santa Monica, Calif., a corporation of Maryland No Drawing. Filed May 4, 1964, Ser. No. 364,787 12 Claims. (Cl. 260955) This invention relates to certain polyfluorophenyl phosphate esters and is particularly concerned with the provision of a novel class of pentafluorophenyl phosphates.

It is an object of the present invention to provide a series of compounds having high fire resistance, high temperature stability, and which remain in liquid form over a wide temperature range and are relatively nonvolatile at elevated temperatures.

Another object of the invention is the provision of polyfluorinated phosphate esters having the above-noted properties and other advantages, and having particular utility as hydraulic fluids or components thereof, heat transfer fluids, and as lubricants.

Other objects and advantages will appear hereinafter.

We have discovered that the above-noted objects are achieved according to the invention by the provision of a class of pentafluorophenyl phosphates having the formula I i 0 OR where R and R are each a member selected from the group consisting of pentafluorophenyl and alkyl. Such alkyl group includes straight chain and branched-chain alkyls and contains, for example, from 1 to about 12 carbon atoms, preferably from about 4 to about 9 carbon atoms. Thus, for example, such alkyl group can be methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, isopropyl, isobutyl, isoamyl, 2-ethyl butyl, LZ-dimethyl butyl, Z-methylpentyl, l-ethylpentyl, l-methylhexyl, Z-ethylhexyl, and the like. R and R can be the same or different. Both R and R can be pentafluorophenyl; both R and R can be alkyl either the same or different; and R can be pentafluorophenyl and R can be alkyl.

Preferred phosphate esters according to the invention are the dialkyl pentafluorophenyl phosphates having the formula I I 0 OR where R" and R are each an alkyl group either straight chain or branched-chain, containing from 1 to about 12 carbon atoms, preferably about 4 to about 9 carbon atoms, as described above.

It has been found that the above-defined pentafluorophenyl phosphates are particularly valuable as functional fluids, e.g., as base stocks for hydraulic fluids, and are also useful as heat transfer media and as lubricants due to the advantageous physical properties of such compounds. These properties include high fire resistance, increased temperature stability, and liquidity over a relatively wide temperature range. Thus, for example, generally these fluorinated phosphate esters have a thermal stability in the range of about 400 to about 700 F., have autoignition temperatures up to and in excess of 1000 F. and remain liquid down to a temperature of the order of -40 to 100 F. Further, the viscosity of such pentafluorophenyl phosphate esters at low temperatures of the order of -40 to 100 F. permits the operative use of such liquids as hydraulic fluids, cooling media and lubricants in these low temperature ranges. These compounds are also relatively non-volatile at elevated temperatures due to the high boiling point of these materials. Also, the phosphate esters of the invention, particularly the dialkyl pentafluorophenyl phosphates, have relatively low pour points, e.g., of the order of F. to F. or lower, which, together with the relatively low viscosity of these materials at low temperatures, permit the liquid compounds to be pumped without high expenditure of energy at low temperatures. Moreover, the phosphate esters of the invention have good hydrolytic stability, and do not adversely affect materials, such as metals, e.g., steel, copper, and the like, wit-h which they may be in contact. These improved properties are believed to be due in large measure to the presence of the pentafluorophenyl radical or radicals in the phosphate esters of the invention.

draulic fluids, lubricants and heat transfer media, e.g., systems, especially modern highspeed aircraft systems.

The monoalkyl or dialkyl pentafluorophenyl phosphate esters of the invention are produced by reacting the cor responding aliphatic alcohol with either pentafluorophenyl phosphoryl dichloride or bis(pentafluorophenyl) phosphoryl chloride, preferably in the presence of pyridine or any other suitable HCl acceptor. The proportion of HCl acceptor or pyridine generally employed is usually about equimolar with respect to the polyfluorinated alcohol. Where it is desired to prepare the preferred dialkyl phosphate esters,

chloride is employed. Where it is desired to prepare the bis(pentafluorophenyl) monoalkyl phosphate esters, bis- (pentafluorophenyl) phosphoryl chloride is used, and a portion of about one mole of the alcohol to one mole of the phosphoryl chloride is utilized.

phosphorus oxychloride in a proportion of about 3 moles of the pentafluorophenol to one mole of the POCl I (1) e s m a):

( (CsFsOhiiOCzHs II (3) CoFsOP(OCH2C 2C a)2 ii CaF5OP(O CHICHiCHiCHB)? ii (5) (CsF50)2POCH2CHnCHs ii (6) CHFSOPlOCHZCH CH3 CH31Q ii (CtsFsOhPOCHflCHZMCHa ii (8) CeFbOP[OCHzOH(C2H5) CHzCHa]:

ii (CaF50)zPOCH2(CHz) 50H;

11 (10) C6F5OP[O CH2CH(CH3) CH2CH2CH7CH3]:

ii (11) CaF5OP[O CHzCIHCzHi) CHzCHnCHzCHs]:

ii (12) (CsF50)aPOCH2(CHz)&CHa

ii (13) (CsF50)zPOCH2CH(CH3) CHKCHQQCH;

ll (14) CaF5O P[O CHflCHahCHa]:

ii (15) (CuFsOhP O CH2(CH2)5CH3 (l)l OCH2CHzCHzCH3 CoFaO P\ O CHaCHgCHs O O CH2(CH2)'3CH5 CuFsO P OCH:(CH1)4CH3 ii (18) (CaF50)aP O CHflOHzhCH;

ii (19) CaFaO P[O 01130111632115) CHflCHgMCHa]:

ii (CeF50)2P O CH3(CH2)10CH:

(l) OCaHi CuFsO P OCH2(CH2)@CH (22) sFaO)sP=O Some preferred compounds of the invention are, for example, compounds (4), (5), (6), (8) and (11).

The following are examples of preparation of the compounds of the invention:

EXAMPLE 1 Dibutyl pentafluorophenyl phosphate To a mixture of 13.8 g. (0.186 mole) of redistilled nbutyl alcohol, 14.7 g. (0.186) mole of pyridine, and 35 ml. of benzene were added dropwise with stirring 25.4 g. (0.0844 mole) of pentafluorophenyl phosphoryl dichloride. The temperature was maintained at 26-43 C. during the addition, which was complete in 45 minutes. The mixture was mixed for 15 minutes at 30 C., then heated to reflux temperature and allowed to reflux overnight. The mixture was then cooled and poured into four times its volume of water. The bottom organiclayer was drawn off and the aqueous layer was extracted with one 80 ml. portion and two 20 ml. portions of ether; these ether extracts were then added to the organic layer, which was then washed with successive 20 ml. portions of 5% hydrochloric acid, water, and 5% sodium bicarbonate. After drying over anhydrous magnesiumsulfate, the solvents were evaporated on a steam bath, and the residue was distilled at 015-016 1 2 me cury. The main fraction of Bis(pentaflu0r0phenyl) butyl phosphate The procedure of Example 1 is substantially carried out except employing about 0.09 mole of n-butyl alcohol and about .09'rnol bis(pentafluorophenyl) phosphoryl chloride, instead of the pentafiuorophenyl phosphoryl dichloride.

The product produced, consisting essentially of compound (5) above, bis(pentafluorophenyl) butyl phosphate, has satisfactory viscosity at low temperatures, low pour point, good thermal stability, high autoignition temperature, good hydrolytic stability, Such phosphate is useful as a base stock for a hydraulic fluid of an aircraft system.

EXAMPLE 3 T ris(pentaflu0r0phenyl) phosphate To 97.2 g. (0.528 mole) of pentafiuorophenol were added dropwise with stirring 153.5 g. (1.00 mole) of redistilled phosphorus oxychloride. The temperature was maintained at 202=6 C. during the addition, which was complete in hour. The mixture was then refluxed for one hour at 129 C., then cooled to C., and maintained at 120 C. for 66 hours. The mixture was heated to C. for 21 /2 hours and then cooled. The phos-. phorus oxychloride was removed by distillation at atmospheric pressure. The residue was distilledvat lower pressure. The tri(pentafluorophenyl) phosphate, 26.8 g., distilled at 164-168 C. at 1 mm. mercury.

The resulting material, consisting essentially of tris- (pentafluorophenyl) phosphate, compound (22) above, has good thermal stability, high autoignition temperature, good hydrolytic stability, and high fire resistance. Such phosphate is useful as a base stock'component for a hydraulic fluid of an aircraft system, and as a lubricant.

EXAMPLE 4 Example 3 is repeated, except employing 0.22 mole of pentafluorophenol and about 0.07 mole of phosphorus oxych1oride,'i.e., about a 3 molar ratio of the pentafluorophenol to the phosphorus oxychloride, to obtain about 11 phenyl) phosphate.

EXAMPLE 5 The procedure of Example 1 is repeated, except employing a mixture of alcohols consisting of 0.09 mole amyl alcohol and 0.09 mole hexyl alcohol, instead of n-butyl alcohol. The product obtained is compound (17) above. This material has satisfactory viscosity at lowtemperatures, low pour point, good thermal stability, high autoignition temperature, good hydrolytic stability, and high fire resistance. Such phosphate is useful as a base stock for a hydraulic fluid of an aircraft system.

EXAMPLE 6 The procedure of Example 1 is substantially repeated, except employing the same molar amount of the following respective alcohols:

The procedure of (a) n-propyl alcohol (b) isobutyl alcohol (c) 2-ethyl butanol and high fire resistance.

grams of tris(pentafluoro- The products produced are, respectively, compounds and Such compounds are useful as hydraulic fluids, lubricants and/ or heat transfer media.

EXAMPLE 7 The procedure of Example 1 is substantially repeated, except employing about .09 mole bis(pentafluorophenyl) phosphoryl chloride and about 0.09 mole of each of the respective alcohols:

(a) ethanol (b) pentanol (c) heptanol (d) octanol (e) isononyl alcohol (f) Z-methyl octanol (g) undecanol The products produced are, respectively, and

From the foregoing, it is seen that the invention provides a novel class of pentafluorophenyl phosphates which are designed particularly for use as base stocks or base stock components of hydraulic fluids in aircraft systems, and which are also useful as lubricants and as heat transfer or cooling media in aircraft systems.

While we have described particular embodiments of our invention for the purpose of illustration, it should be understood that various modifications and adaptations thereof may be made within the spirit of the invention, as set forth in the appended claims.

compounds We claim:

1. A phosphate having the formula F F I fi/OR F OP Where R and R are each a member selected from the class consisting of pentafluorophenyl and alkyl groups.

2. A phosphate as defined in claim 1, said alkyl groups containing from 1 to about 12 carbon atoms.

3. A phosphate as defined in claim 1, said alkyl groups containing from about 4 to about 9 carbon atoms.

4. A compound as defined in claim 1, wherein R is pentafluorophenyl and R is alkyl containing from 1 to about 12 carbon atoms.

*5. A compound as defined in claim .1, wherein R is pentafluorophenyl and R is alkyl containing from about 4 to about 9 carbon atoms.

6. A phosphate having the formula I 0 OR where R and R'" are each an alkyl group containing from 1 to about 12 carbon atoms.

7. A phosphate as defined in claim 6, wherein said alkyl groups contain from about 4 to about 9 carbon atoms.

8. Dibutyl pentafluorophenyl phosphate. 9. Tris(pentafiuorophenyl) phosphate. 10. Di(-2-ethyl butyl) pentafluorophenyl phosphate. 11. Di( 2-ethyl hexyl) pentafluorophenyl phosphate. 12. 'Dioctyl pentafluorophenyl phosphate.

No references cited.

CHARLES B. PARKER, Primary Examiner. ANTON H. SUTTO, Assistant Examiner. 

1. A PHOSPHATE HAVING THE FORMULA 